• 作者： 曾祥光
• 作者服務機構： 中央大學物理系,物理與天文研究所
• 中文摘要： 以分波方法數值計算所得結果，我們檢討入射電子動能為一千電子伏特以上原子場中電子制動輻射光子能量微分截面積及光子能量與角度微分截面積的現有理論情況。我們研討了簡單理論的可靠性。由於能量譜兩端點對描述能量譜特性的重要，我們研討了能量譜兩端點的性質。Bethe-Heitler 公式僅可用於低原子序元素及遠離高頻率區的高能量情況或角分佈的形狀。以波形因數修正屏蔽與以Elwert因數修正庫倫效應的 Born近似法對低原子序元素可做定值的預計，而對高原子序元素而言僅可做定性的預計。Sommerfeld 公式對點庫倫情況時可用於電子動能至五萬電子伏特。在高能量時我們可用 Bethe-Maximon 使用 Sommerfeld-Maue 波函數所得的高能公式；而 Elwert -Haug使用該函數推廣到中能量區的近似公式則適用於角分佈，且為目前制動輻射基本過程截面積的最佳理論預計。 在實驗方面近年來已有制動輻射角分佈，光子與入射電子間的極化強度相關係數及基本過程截面積的數據。前二種實驗結果與我們的分波結果相符合，雖然還有一些不相符合的情況有待解釋。
• 英文摘要： A review of current theoretical status of atomic field electron bremsstrahlung is presented in termsor its cross section as and its differential cross section d for incident-electron kinetic energies above 1keV. This review is based on an exact numerical calculation in a partial-wave formulation. Validity ofsimpler theories is examined. The properties of the two endpoints of the spectrum is investigated in detail.We have found that the Bethe-Heitler formula may be used only for low atomic-number Z elements andhigh energy away from the tip, or for the shape of the angular distribution d . Born approximation com-bined with the Elwert factor and the form factor is quantitatively correct for low Z, and qualitatively usefulfor high Z. The Sommerfeld formula is acceptable for point-Coulomb case up to 5O keV. For higherenergies the high energy limit obtained by Bethe and Maximon using Sommerfeld-Maue wave functions isavailable. Its approximate extension to intermediate energy by Elwert and Haug, usable for d , providesthe best available result for the triply differential cross section d . Recent experimental work is available for d , the corresponding polarization correlations, and thetriply differential cross section d . The first two types of experiments are in good agreement with ourpartial-wave results, although various residual discrepancies remain to be explained.
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